The field of the invention relates to phase locked loop frequency synthesizer circuits and methods for intertransmission of data between modems on a local information network.
In particular, the invention relates to broadband RF modems and circuitry for transmitting and receiving data on frequencies unique to each modem. Further, the invention relates to a network of these modems which may be interconnected by a passive transmission medium as well as a method which may be utilized to effectuate intercommunications therebetween.
There have previously been proposed various modem configurations and local networking schemes for intercomputer communications. Among these is a baseband local network in which the entire bandwidth of a cable transmission medium is utilized for the intertransmission of data between modems. Various proposals have been made for a networking scheme of such units including establishing a head end to the network which then routinely polls the various modems for information. Other networks have included a series connected system in which information is retransmitted successively from one modem to another until reaching its intended receiver. Alternatively, collision detection multple access (CDMA) may be utilized in which information which is transmitted by one unit is monitored by the same transmitting unit to ensure that it is not garbled by another transmission occurring simultaneously. While high data rates are possible with such baseband systems due to the large bandwidth inherent in the transmission medium, such large data rates are not always needed in a local network. Further, the overall throughput of data through the system can be significantly reduced by numerous transmission collisions.
As an alternative, a broadband system has been proposed which divides the bandwidth into separate and distinct channels allowing for multiple concurrent transmissions between modems on the network. Such units are concomitantly more complex and have been relatively costly to produce, requiring separate transmit and receive frequency synthesis of the various frequencies involved. Conventional frequency synthesis techniques have proven cumbersome in this regard and previous methods for fully utilizing a broadband system have not proven entirely satisfactory.
It would therefore, be highly desirable to provide an improved phase locked loop frequency synthesizer circuit and method for intercomputer communication on a local network of broadband RF modems.
It would further be highly desirable to provide an improved phase locked loop frequency synthesizer circuit and method for intercomputer communication on a local network of broadband RF modems which is readily and inexpensively fabricated and effectuated.
It would still further be highly desirable to provide an improved phase locked loop frequency synthesizer circuit and method for intercomputer communication on a local network of broadband RF modems which can accurately synthesize multiple transmit and receive frequencies for the encoding and decoding of data thereon.